Process for producing 11alpha-hydroxy steroids



United States Patent 0 PROCESS FOR PRODUCING Ila-HYDROXY STEROIDS Franz Sondheimer, Mexico City, Mexico, Carl Dierassi, Birmingham, Mich., and George Rosenkranz and Octavio Mancera, Mexico City, Mexico, assignors to Tgaynt ex S. A., Mexico City, Mexico, a corporation of exico No Drawing. Application July 28, 1953, Serial No. 370,855

Claims priority, application Mexico August 2, 1952 17 Claims. (Cl. 260239.55)

The present invention relates to a novel method for the preparation of cyclopentanophenanthrene derivatives. More particularly, the present invention relates to a novel method for the preparation of steroidal 11ahydroxy compounds from the corresponding ll-keto compounds.

As is well known, the lla-hydroxy compounds are valuable intermediates for the production of cortical hormones, for example, llu-hydroxy progesterone which is produced biochemically from progesterone, has by known methods been utilized for the production of cortisone. Since the biochemical oxidation produces, in general, llu-hYdI'OXY compounds in many instances, it is desirable to have a method for producing these same compounds synthetically so that the compounds of the present invention are not only useful intermediates, as is wellknown, but the present process also presents a useful method for preparing these known compounds.

It is well-known that most of the methods for the "ice reduction of a keto group at position 11 of the steroidal molecule, as for example the reduction with lithium aluminum hydride, produces the corresponding 11,8- hydroxy compound. In the United States application of Sondheimer, Djerassi and Rosen-lcranz, Serial No. 335,586, filed February 6, 1953, there has been described a method for the transformation of certain specific steroidal A -11-keto compounds into the corresponding saturated lla-hydroxy compounds by treating the same with alkali metal in ammonia solution and in the presence of an alcohol. It was generally considered that this method was only suitable for the production of lla-hydrox'y saturated compounds from the corresponding A -ll-keto compounds, particularly of the allo series at 'C-5.

In accordance with the present invention, the surprising discovery has been made that steroidal 11ozhydroxy compounds may be produced from the corresponding saturated ll-keto compounds irrespective of the configuration and other active positions in the molecule. Particularly, this surprising discovery has been made that the configuration at C-5 has no influence on the course of the present reaction and that the reaction of an ll-keto compound with alkali metal in ammonia solution in the presence of alcohol produces in good yield the corresponding lla-hydroxy compound whether or not the steroid belongs to the C-5 normal series or the C-5 allo series.

It has been further discovered in accordance with the present invention that other substituents may be present in the molecule and that other substituents, such as a keto group, may be protected from reaction with the reducing agent by the formation of a ketal or a 'hemithioketal, thereby making possible the selective reduction of the keto group at position 11.

The following equations illustrate typical examples ofthe application of the present method:

CH: O-CH:

Kl. n I

l i R O l R I l I O-CH:

HO I

thereto in small portions. After each addition the blue color produced is allowed to disappear before the next portion is added. Ammonium chloride is then added.

and theammonia, is thenevaporated by heating on "a steam bath. The product is then purified and the crystalline precipitate, if a ketal, can then be treated as.

with acid to decompose the ketal- In any event; the corresponding lla-hydroxy compound is produced in good yield. If the steroid possesses an esterified hydroxy groupas is indicated by R in the above equations, thenpreferably the product is reesterified since the method produces to a certain extent a saponification of esterified hydroxy groups. Preferably R in the above vequa: tions represents the esterification'residue of any acid normally used for the esterification of steroids alcohols, as for example, R,may represent the residue of a" lower fatty acid such as acetic or the residue of benzoic acid.

The above equations are intended to represent only typical examples of steroids audit is obvious that other other side chains may be present at 16 or 17.

The following specific examples serve-to illustrate but are not intended to limit the presentinvention:

Example I r "A solution of 1 g. of the 20-monoethylene ketal of regnane-3q-ol-1L20-dione having a melting point of 144146 C. in cc. of ether andgS cc. of methanol was added to 100 cc. of liquid ammonia. While the mixture wasmechanically stirred, 0.5 g. of lithium metal were added in small portions, waiting for the blue, color to disappear before adding the next portion. Then 5 g. of ammoninum chloride were slowly added and the,

ammonia was evaporated by heating on the steam. bath. The residue was dilutfid with water and the product was extracted with ether and well washed with water until removal of all the ammonia. The ether solution was dried over sodium sulfate, concentrated to cc. and cooled. The crystalline precipitate of the 20-ethyleneketal of pregnane-3a,1la-diol-ZO-one Was filtered, thus giving 0.86 g., melting point l93-197 C. Re-

50 crystallization from acetone-hexane raised the melting ture.

to dryness.

point to 199-200 C., [al +15.83 (chloroform).

740 mg. of the 20-ethyleneketal of pregnane-3e,11ccdiol-20-one were dissolved in 50 cc. of anhydrous acetone containing 75 mg. of p-toluenesulphonic acid and the mixture was kept for 24 hours at room tempera- It was then poured into water and the product was extracted with chloroform, washed several times with water, dried over sodium sulfate and evaporated Recrystallization of the residue from acetone-hexane yielded 0.65 g. of pregnane-3a,11a-diol-20- one with a melting point of 178-179 C., [ul +88 (chloroform).

Acetylation with acetic anhydride in pyridine by known methods afforded the corresponding diacetate with a melting point of 142-144 C., [at] +6l (chlorosubstituents may be present/on the basic molecule and o form).

, p, Example II Following the method described in Example I for the reduction of the 20-monoethyleneketal of pregnanc- 3m-ol-1l,20-dione, there was reduced 1 g. of 22-isoallospirostane-3fi-0l-ll-one acetate. The resulting prodnot which was dilficult to crystallize was directly acetylated by heating for one hour on the steam bath with 3 cc. of acetic anhydride and 2 cc. of pyridine. Isolation by routine methods gave 0.69 g. of 22-isoallospirostane-BfiJM-diol diacetate with a melting 30 point of 172-174 C., [ab 77' (chloroform), which was identical with an authentic sample.

Example 111 1 g. of the ZO-monoethyleneketal of allopregnane-3B 35 ol-11,20-dione acetate (the preparation of which is de- 5 scribed in a paper of Djerassi, Batres, Rome and Rosenkranz, Jour. Amer. Chem. Soc., 1952), was treated in exactly the same way as described in Example I, except that sodium metal was used instead of lithium metal. After hydrolizing the ketal and reacetylating, there was obtained allopregnane-3,8,1let-diol-20-one diacetate with a melting point of 169171 (1., [:11) +43 (chloroform) in a yield of 0.7 g.

Example IV 1 g. of the 20-monoethylenehemithioketal of allopregnane-3fi-ol-11,20-dione acetate (the preparation of which is described in the above mentioned paper of Djerassi et al.) was treated by the same method described in the previous example, thus giving allopregnane- 33,11a-diol-20-one diacetate, identical to the one obtained in accordance with Example III.

Example V 1 g. of the ZO-monoethyleneketal of allopregnane- 3B,l7a-diol-1l,20-dione was treated in exactly the same way as described in Example I, yielding 0.58 g. of allopregnane-3p3,11a,17c-triol-20-one with a melting point of 250253 C. Recrystallization from ether raised the melting point to 253255 C.

Example VI Starting from 1 g. of A -pregnene-3,l1,20-trione (llketo progesterone) there was prepared the 3,20-diethyleneketal by known methods, for example by the method described in the United States application of Dauben, Ringold and Loken, Serial No. 364,216 filed June 25, 1953. l g. of the crude 3,20-diethyleneketal was treated in exactly the same way as described in Example I, giving 0.65 g. of N-pregnene-l1a-ol-3,20-dione (lla-hydroxyprogesterone) with a melting point of 163 l66 C., raised to 166167 C. by one recrystallization.

Example VII 1 g. of the 3,20-diethyleneketal of M-pregnene, 3,11,20-trione was treated by the method described in Example I, except that lithium metal was substituted for potassium metal, giving the same lltz-hydroxyprogesterone in a slightly lower yield than that described in the previous example (0.6 g.).

We claim:

1. A method for the production of steroidal 11ahydroxy compounds which comprises reducing the corresponding steroidal ll-keto compounds with an alkali metal in ammonia solution and in the presence of an alcohol.

2. The method of claim 1 wherein the alkali metal is lithium.

3. The method of claim 1 wherein the alkali metal is sodium.

4. The method of claim 1 wherein the alkali metal is potassium.

5. The method of claim 1 wherein the steroidal llahydroxy compound has the normal configuration at C-5 .and is produced from the corresponding C-5 normal ll-keto compound.

6. The method of claim 1 wherein the steroidal llahydroxy compound possesses the allo configuration at C-5 and is produced from the corresponding ll-keto compound.

7. A method for the selective reduction of a steroidal ll-keto compound having additional keto groups in the molecule which comprises forming a derivative of such additional groups selected from the group consisting of the hemithioketals and ketals thereof, reducing the derivative with an alkali metal in liquid ammonia in the presence of an alcohol to prepare the corresponding steroidal lla-hydroxy derivative and cleaving said derivative.

8. The method of claim 7 wherein the steroidal compound is a member of the pregnane series.

9. The method of claim 7 wherein the steroidal compound is a member of the allopregnane series.

10. The method of claim 7 wherein the steroidal compound is a member of the normal pregnane series.

11. A method of or the preparation of pregnanc- 3a,11a-di0l-20-one which comprises reducing the 20- monoethyleneketal of pregnane-3a-ol-11,20-dione with lithium metal in solution in ammonia in the presence of methanol, and thereafter cleaving the ketal group.

12. A method for the preparation of 22-isoalzlospirostan-3fi,lla-diol, which comprises reducing 22- isoallospirostan-Sfi-ol-l l-one with lithium metal in solution in ammonia in the presence of methanol.

13. A method for the preparation of allopregnane- 3,6,1la-diol-20-one which comprises reducing the 20- rnonoethyleneketal of allopregnane 3 3 ol 11,20 dione with sodium metal in solution in ammonia in the presence of methanol and thereafter cleaving the ketal group.

14. A method for the preparation of allopregnane- 3B,lloc-dl0l20-0Il8 which comprises reducing the 20- monoethylenehemithioketal of allopregnane-3fi-ol-l1,20- dione with sodium metal in solution in ammonia in the presence of methanol and thereafter cleaving the ketal group.

15. A method for the preparation of allopregnane- 3B,1loc,17a-lfiOl-20-OI1 which comprises reducing the 20-monoethyleneketal of allopregnane-3B,17a-diol-11,20- dione with lithium metal in solution in ammonia in the presence of methanol and thereafter cleaving the ketal group.

16. A method for the preparation of M-pregnene-lhol-3,20-dione which comprises reducing the 3,20-diethyleneketal o-f A -pregnene-3,11,20-trione with lithium metal in solution in ammonia in the presence of methanol and thereafter cleaving the ketal groups.

17. A method for the preparation of A -pregnene-11aol-3,20-dione which comprises reducing the 3,20-diethyleneketal of A -pregnene-3,11,20-trione with potassium metal in solution in ammonia in the presence of methanol and thereafter cleaving the ketal groups.

No references cited. 

1. A METHOD FOR THE PRODUCTION OF STEROIDAL 11AHYDROXY COMPOUNDS WHICH COMPRISES REDUCING THE CORRESPONDING STEROIDAL 11-KETO COMPOUNDS WITH AN ALKALI METAL IN AMMONIA SOLUTION AND IN THE PRESENCE OF AN ALCOHOL. 